This invention relates to interposers, the transitional circuit cards between integrated circuit dice, such as microprocessors, as an example, not a limitation, and a motherboard upon which they are to be mounted, often through connectors.
Prior art interposers are made as multilayer printed wiring boards with traces etched on planar conductor surfaces and with vias to connect from layer to layer. The need to use vias requires that circuit traces be reduced in width to provide clearance for vias that pass closely but do not connect. Vias in interposers tend to be very small and thus have high resistance.
Prior art interposers often have many hundreds of connections, and often many hundreds of the connections are devoted to power and ground connections. Despite the large number of parallel connections used, the impedance in the power circuits is quite high, in the order of 340 μΩ. In that the voltage used by processors is very low, in the order of 1 v, and the current is very high, in the order of 100 a peak, this is a significant problem.